A projection apparatus includes an inputting unit configured to input image data that expresses an image to be projected; a converting unit configured to convert pixel values of the image data into first parameters that indicate lightness and second parameters that indicate information concerning color; a determining unit configured to determine whether to invert the first parameters; an inverting unit configured to invert the first parameters to calculate third parameters if the determining unit has determined to invert the first parameters; a generating unit configured to generate inverted data based on the second parameters and the third parameters; and a projecting unit configured to project the image based on the inverted data.